arXiv subjects

Jiwon Park

Publications and source records attributed to Jiwon Park.

23 records · Page 2Linked to original sources

arXiv2020

Probing Primordial Symmetry Breaking with Cosmic Microwave Background Anisotropy

There have been vigorous research attempts to test various modified gravity theories by usingphysics of the cosmic microwave background (CMB). Meanwhile, symmetry breaking such as Higgsmechanism is one of the most important phenomena in physics but there have been not so muchresearches to make them contact with cosmological observations. In this article, with the CMBpower spectra we try to distinguish two different scenarios of spontaneous symmetry breaking inprimordial era of the universe. The first model is based on a broken symmetric theory of gravity,which was suggested by A. Zee in 1979. The second model is an application of Palatini formalismto the first model. Perturbation equations are computed and they show differences originated fromthe property of symmetry. Furthermore, it turns out that two models have different features ofCMB power spectra with the same potential scale. This fact enables us to verify distinct kinds ofprimordial symmetry breaking with CMB physics.

gr-qc↗

arXiv2020

Dynamical analysis of Brans-Dicke Universe with inverse power-law effective potential

We study Brans-Dicke cosmology with an inverse power-law effective potential. By using dynamical analyses, we search for fixed points corresponding to the radiation-like matter and dark energy-dominated era of our Universe, and the stability of fixed points is also investigated. We find phase space trajectories which are attracted to the stable point of the dark energy-dominated era from unstable fixed points like matter-dominated era of the Universe. The dark energy comes from effective potentials of the Brans-Dicke field, whose variation (related to the time-variation of the gravitational coupling constant) is shown to be in good agreement with observational data.

gr-qc↗

arXiv2019

Correlation between $R_{D^{(*)}}$ and top quark FCNC decays in leptoquark models

Some interpretations of $R_{D^{(*)}}$ anomaly in $B$ meson decay using leptoquark (LQ) models can also generate top quark decays through Flavor Changing Neutral Current (FCNC). In this work we focus on two LQs, i.e. scalar $S_1$ and vector $U_1$ which are both singlet under the $SU(2)_L$ gauge group in the Standard Model (SM). We investigate their implications on the 3-body top FCNC decays $t\to c \ell_i \ell_j$ at tree level and the 2-body $t\to c V$ at one-loop level, with $\ell$ being the SM leptons and $V=γ, Z, g$ being the SM gauge bosons. We utilize the $2σ$ parameter fitting ranges of the LQ models and find that $Br(t\to c \ell_i \ell_j)$ at tree level can reach $\mathcal{O}(10^{-6})$ and $Br(t\to c V)$ at one-loop level can reach $\mathcal{O}(10^{-10})$. Some quick collider search prospects are also analyzed.

hep-ph↗

arXiv2018

Proceedings of the first MadAnalysis 5 workshop on LHC recasting in Korea

We present the activities performed during the first MadAnalysis 5 workshop on LHC recasting that has been organized at High 1 (Gangwon privince, Korea) on August 20-27, 2017. This report includes details on the implementation in the MadAnalysis 5 framework of eight ATLAS and CMS analyses, as well as a description of the corresponding validation and the various issues that have been observed.

hep-ph↗

arXiv2016

Phase transition in anisotropic holographic superfluids with arbitrary $z$ and $α$

Einstein-dilaton-$U(2)$ gauge field theory is considered in a spacetime characterised by $α$ and $z$, which are the hyperscaling violation factor and the dynamical critical exponent respectively. We obtain the critical values of chemical potential $μ_c$ that is defined on its boundary dual fluid and derives phase transition from spatially isotropic to anisotropic phase for the various values of the $α$ and $z$. To do so, we first apply Sturm-Liouville theory and estimate the upper bounds of the critical values of the chemical potential. We also employ a numerical method in the ranges of $1 \leq z \leq 4$ and $0 \leq α\leq 4$ to check if the Sturm-Liouville method correctly estimates the critical values of the chemical po10 percent error ranges. Finally, we compute free energy density of the dual fluid by using its gravity dual and check if the system shows phase transition at the critical values of the chemical potential $μ_c$ for the given parameter region of $α$ and $z$. Interestingly, it is observed that the anisotropic phase is more favoured than the isotropic phase for small values of $z$ and $α$. However, for large values of $z$ and $α$, the anisotropic phase is not favoured.tential. It turns out that the two methods are agreed within

hep-th↗